vintage chromoly

iTrader: (3)

Hello all.
Starting to rig my 24/7 pantera.
I need to figure out what type of freshwater pickup to use. I noticed the "through the bottom" stainless flush mount pickups are often mentioned for secondary water pickup (intercooler) and I wonder if they are sufficient for the main engine cooling pickup.

I have a mercury racing stainless strainer with 1.25 pipe threads and a mercruiser engine mounted seawater pump.

Questions:

What size should an engine cooling pickup be? 1.25?

Is a transom or through bottom pickup better?

Should I use a crossover with a bypass and t-stat or run a non-bypass and no stat?

Boat is a 517 bbc with a bravo drive. Lake Erie usage.

Thanks guys.

dereknkathy

all sportfish use thru bottom pickups, but the chance of them leaving the water all the way to the transom aren't very good. so you would want it as far aft as possible, as close to keel as possible, and where it wouldn't interfere with trailer rollers-bunks.

BenPerfected

We switched from the transom mount WPU to the Stainless Marine thru bottom PU. The data we gathered said there was a potential of +1-2 MPH at 90+ MPH in a vee. We had too many changes going on at the same time to confirm, maybe the race teams have better opinions. For sure it is a cleaner install. Our boat is a straight vee, the water PU point would likely be more critical in step bottom application.

vintage chromoly

iTrader: (3)

Would a good location be just to the starboard of the delta pad and 6 to 8 inches forward of the tansom?

Also, what size?

Thanks, rob

BenPerfected

You want the PU's to be in mostly in solid water. It sounds to me like the location you are selecting might be in a good position. At speed the hull is lifting so you don't want to get too far outside the CL. Out PU's are about 6-8" from the CL and directly behind but to the side of a small lifting pad. Can you find someone with experience on how your Delta pad drys out the bottom of your boat? That would be a good question to ask the boat manufacture. I think the SM thru hull PU's are 1" but each PU supply's enough enough water with 1-1/4" hose to the sea strainers at 6500+ RPM to feed two stage water pumps. We can hold enough water pressure that we still have bleed off water at the intake manifold even with large water dumps at the end of the tails.

kevinb230

Mine is on the transom, it makes it easy to check for junk

vintage chromoly

iTrader: (3)

Thanks for the replies fellas.

I'm leaning toward a through the bottom unit.

Any other suggestions or input?

SkiDoc

iTrader: (4)

With the through hull, you will need to cut a channel which funnels water into the pickup. Not a tremendously big deal but it will need to be at least .25 deep an like 8-10 inches long. You will have to install either a permanent or temporary waterpress. guage and test to achieve proper water pressure. The deeper the groove the more wp you will see. After you get it right then you gel coat. Another thing you need to think about is that per coast guard regs, the through hulls should have a cutoff. Do you have enough room with oil pan, etc.. for this. You want to be able to service this pretty easy. What happens if the through hull location will not reliably supply water. Then you may need to pull engine to relocate. Transom may be the best or the least hassle.

vintage chromoly

iTrader: (3)

The boat will have a shutoff valve regardless of what pickup I use.
I have a permanent h2o gauge.

Maybe a transom mount would be better as I've already blueprinted and gelcoated the bottom.

I was doing internet research an some suggest that the groove is unnecessary. The pickup will always be under water. One guy said he ended up filling in the groove as the water pressure was extremely high with the groove.

I plan on using a relief valve to ensure I don't over pressurize the system.

BenPerfected

We started with a 6-8" tapered groove in front of the thru-hull PU but had too much WP. After a couple of redesigns filled it in and still had to bleed WP at the intake. The vacuum created by the sea water pump was more than sufficient. We put the water cut-offs directly on the SM PU. There is also a tee fitting between the cut-off and 1-1/4" hose to allow the flush or run the engines off a water hose.